When I want to read a book, I can just do that. When I play a game, I want it to have gameplay. Tworment makes you go through many hours of reading between moments of actually getting to play the game, and the reading isn't interesting. The setting fails because every square foot of it is screaming "hey look at how weird this thing is", and when everything is weird the weird becomes mundane. It doesn't feel like a world people live in, it feels like a creative writing major has cornered you and is now assaulting you with every idea he's ever come up with.
Most of that holds true for the PS:T too though, right?
So what makes Numera suck? World less interesting?